With the number of bolts breaking and the need for the ARF to replace them (plus the obvious safety risk) - doesnt it make sense to make a standard rule that only stainless steel bolts should be used for bolting / replacement of old bolts? I know it would be more expensive, but in the long run I think it would be way cheaper (as an additional advantage, it may also cause people to use bolts more sparingly, which will please some)

Most if not all the bolts that have failed are stainless 304 grade expansion bolts. the answer is 316 marine grade stainless expansion bolts that are not overtightened, or stainless glue-ins that the ARF is using. glue-ins are more complex to install but cannot by definition be overtightened. check out the ARF post on SCC http://www.climbing.co.za/arf.asp.

316 Marine grade stainless sounds good, but I am surprised that the 304 stainless doesnt last (we have a 304 stainless braai at the coast that is twenty years old with no signs of any trouble so in my opinion the material is good) - what I am wondering is that possibly the 304 stainless bolts have not been stress relieved after manufacture? Hopefully this is done with the 316 bolts as we may end up with the same problem again?

I am convinced that ss304 is good enough for most environments without a high concentration of chloride in the air (eg.cape town ). If the bolt is not over tightened and left permantly stressed with high concentration of chloride there is no reason ss304 should be susseptible to scc.

Mark I am perplexed by your 1st post - you imply the failed bolt was not stainless steel - did you look at the pics?

People - I have spent a lot of time investigating this issue and I believe it is well documented in the ARF page. Some very good materials and mechanical engineers have been involved who have SIGNIFICANT experience with Stress Corrosion Cracking. If you want to help deal with this problem you can:

1) NOT use UPAT bolts that are machined and made from 304 stainless
2) NOT over torque bolts
3) Use HILTI / Fischer bolts that are rolled and made from 316 stainless
4) Support ARF

Hi Andy, I did look at the pics and I am no engineer, the head of the bolt looks like shiny stainless but the amount of corrosion / rusting (and right through the bolt) left me under the impression that it was not stainless. It got me thinking about some of the routes I have seen (and not climbed) which have home made mild steel hangers (and who knows what bolts). So I was suggesting that in all cases (joburg the coast etc) that stainless bolts be used and anything else be frowned upon (it wasnt specific to this incident). Then when I heard the bolts that snapped were 304 stainless I was suprised and remembered that stainless undergoes a lot of stress when it is worked with and needs to be stress relieved (and in certain instances x-rayed for stress lines) so I was throwing it out there in case it was useful to anyone (maybe we are only focussing on corrosion at the coast when it is also a general stress issue and may happen inland in a couple years time). So no offense to anyone at ARF I appreciate the effort and I support you guys - I was just adding some food for thought.

Hi Mark this issue has already been thrashed to death in this forum. Perhaps search previous posts before posting in future?

As Andy points out the problems with SCC breakages of bolts has been thoroughly scientifically investigated. Basically it was a combination of the actual design of the bolt and the way it was made, coupled to the tendency of people to overtighten the bolts and proximity to the sea that is causing the failures. I believe the vast majority of the bolts that have already been replaced by the ARF were still sound at the time of removal. Also bear in mind that most of these bolts are over ten years old and have been subjected to forces somewhat beyond those experienced by some braai!

So long as people only use the recommended bolts in future and place them correctly we should see far less if any problems in future. Even if you are bolting inland please still use the recomended 316 bolts. Even sweat from your hand can contain enough chloride to instigate SCC. Again, the standards used in the design and manufacture of many of the 304 bolts are far below those applied to the production of the recommended 316 bolts.

Donate something to the ARF! Viva secure glue-ins!!

PS Titanium bolts were investigated, but are not presently in manufacture.

Why is everyone so defensive about this? I am not attacking what ARF is doing? What I am concerned about is that maybe this problem is not limited to an SCC enironment (where it is accelerated) and possibly it also exists in a normal (non chloride) stress environment and maybe people are using the wrong bolts? (I AM NOT REFERRING TO ARF THEY KNOW WHAT THEY ARE DOING) - So I thought it was relevant in this friendly forum of ours to discuss / highlight the need to use proper bolts (doing my own research wouldnt have achieved this nor would it have made people think twice about who's bolts they are trusting) - my intention was to make the point that as far as bolting is concerned overkill is the best approach ... If no one is worried about general stress / aging / popping of bolts then cool... happy days.... end of thread...

Mark wrote:With the number of bolts breaking and the need for the ARF to replace them (plus the obvious safety risk) - doesnt it make sense to make a standard rule that only stainless steel bolts should be used for bolting / replacement of old bolts? I know it would be more expensive, but in the long run I think it would be way cheaper (as an additional advantage, it may also cause people to use bolts more sparingly, which will please some)

Mark, maybe you get less than over-the-top friendly responses because you show (and acknowledge yourself) that you

Mark wrote:doing my own research wouldn't have achieved this

haven't done any research. This might seem harsh, but you'll find thread upon thread of great quality info from experienced and knowledgeable people if you use the search function.

About making it a standard rule to only use stainless bolts (as opposed to what? galvanised? mild steel? plastic?), if you know of any mild steel expansion bolts around, please let us know (exclude steel u-bolts at Chosspile)

Hi Nosmo, that is harsh, and out of context - I didnt say I didnt do any research, I said if I had quietly researched it by myself the topic would be highlighted to potential bolters.

No-one seems to regulate how things actually get bolted, its just a case of buy bolts and a drill which is dangerous. Bobbejaans berg has some mild steel hangers (without removing the bolts I dont know what they are) in Harrismith I have seen lower offs with common spot welded chain link (which again doesnt give me much hope about the bolt behind it)

There is meant to be a new type of Stainless Steel on the market which doesn't contain Nickel, as a result of Nikkel being expensive they have made a stainless steel without Nickel, it contains something else in its place instead of Nickel, I don't know what. They claim it meant to be corrosion resistant like 316 stainless steel. The information I have is that is has been laboratory tested however the person who told me this at the time said it hadn't been tested in the real world yet and he also said that the real test will be when you put this new type of Stainless Steel near the sea and after a year see what condition it is in. I don't know if anyone knows anything more about this new type of Stainless Steel on the market?

Drifter dude, there are a few types around.... you have to give a number or somethin'

wikipedia wrote:Stainless steel grades
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It has been suggested that this article or section be merged into SAE steel grades. (Discuss)
This list is incomplete; you can help by expanding it.

See also: SAE steel grades

* 100 Series—austenitic chromium-nickel-manganese alloys
o Type 101—austenitic that is hardenable through cold working for furniture
o Type 102—austenitic general purpose stainless steel working for furniture
* 200 Series—austenitic chromium-nickel-manganese alloys
o Type 201—austenitic that is hardenable through cold working
o Type 202—austenitic general purpose stainless steel
* 300 Series—austenitic chromium-nickel alloys
o Type 301—highly ductile, for formed products. Also hardens rapidly during mechanical working. Good weldability. Better wear resistance and fatigue strength than 304.
o Type 302—same corrosion resistance as 304, with slightly higher strength due to additional carbon.
o Type 303—free machining version of 304 via addition of sulfur and phosphorus. Also referred to as "A1" in accordance with ISO 3506.[9]
o Type 304—the most common grade; the classic 18/8 stainless steel. Also referred to as "A2" in accordance with ISO 3506.[9]
o Type 304L— same as the 304 grade but contains less carbon to increase weldability. Is slightly weaker than 304.
o Type 304LN—same as 304L, but also nitrogen is added to obtain a much higher yield and tensile strength than 304L.
o Type 308—used as the filler metal when welding 304
o Type 309—better temperature resistance than 304, also sometimes used as filler metal when welding dissimilar steels, along with inconel.
o Type 316—the second most common grade (after 304); for food and surgical stainless steel uses; alloy addition of molybdenum prevents specific forms of corrosion. It is also known as marine grade stainless steel due to its increased resistance to chloride corrosion compared to type 304. 316 is often used for building nuclear reprocessing plants. Most watches that are made of stainless steel are made of Type 316L. Also referred to as "A4" in accordance with ISO 3506.[9] 316Ti includes titanium for heat resistance, therefore it is used in flexible chimney liners.
o Type 321—similar to 304 but lower risk of weld decay due to addition of titanium. See also 347 with addition of niobium for desensitization during welding.
* 400 Series—ferritic and martensitic chromium alloys
o Type 405— ferritic for welding applications
o Type 408—heat-resistant; poor corrosion resistance; 11% chromium, 8% nickel.
o Type 409—cheapest type; used for automobile exhausts; ferritic (iron/chromium only).
o Type 410—martensitic (high-strength iron/chromium). Wear-resistant, but less corrosion-resistant.
o Type 416—easy to machine due to additional sulfur
o Type 420—Cutlery Grade martensitic; similar to the Brearley's original rustless steel. Excellent polishability.
o Type 430—decorative, e.g., for automotive trim; ferritic. Good formability, but with reduced temperature and corrosion resistance.
o Type 440—a higher grade of cutlery steel, with more carbon, allowing for much better edge retention when properly heat-treated. It can be hardened to approximately Rockwell 58 hardness, making it one of the hardest stainless steels. Due to its toughness and relatively low cost, most display-only and replica swords or knives are made of 440 stainless. Also known as razor blade steel. Available in four grades: 440A, 440B, 440C, and the uncommon 440F (free machinable). 440A, having the least amount of carbon in it, is the most stain-resistant; 440C, having the most, is the strongest and is usually considered more desirable in knifemaking than 440A, except for diving or other salt-water applications.
o Type 446—For elevated temperature service
* 500 Series—heat-resisting chromium alloys